Patchwork C++ PATCH to initializer_list overload resolution

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Submitter Jason Merrill
Date Sept. 18, 2010, 9:24 p.m.
Message ID <4C952DF2.5090906@redhat.com>
Download mbox | patch
Permalink /patch/65138/
State New
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Comments

Jason Merrill - Sept. 18, 2010, 9:24 p.m.
In the test, we were exiting compare_ics early, and therefore failing to 
prefer binding a temporary initializer_list to && over const &.

Tested x86_64-pc-linux-gnu, applied to trunk.

Patch

commit c891c50df00a4a8270a31736e982a3b3475c6b07
Author: Jason Merrill <jason@redhat.com>
Date:   Sat Sep 18 14:39:38 2010 -0400

    	* call.c (compare_ics): Do lvalue/rvalue reference binding
    	comparison for ck_list, too.

diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index 2b9b848..89ab757 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -6859,9 +6859,8 @@  compare_ics (conversion *ics1, conversion *ics2)
       /* We couldn't make up our minds; try to figure it out below.  */
     }
 
-  if (ics1->ellipsis_p || ics1->kind == ck_list)
-    /* Both conversions are ellipsis conversions or both are building a
-       std::initializer_list.  */
+  if (ics1->ellipsis_p)
+    /* Both conversions are ellipsis conversions.  */
     return 0;
 
   /* User-defined  conversion sequence U1 is a better conversion sequence
@@ -6870,16 +6869,24 @@  compare_ics (conversion *ics1, conversion *ics2)
      ond standard conversion sequence of U1 is  better  than  the  second
      standard conversion sequence of U2.  */
 
-  if (ics1->user_conv_p)
+  /* Handle list-conversion with the same code even though it isn't always
+     ranked as a user-defined conversion and it doesn't have a second
+     standard conversion sequence; it will still have the desired effect.
+     Specifically, we need to do the reference binding comparison at the
+     end of this function.  */
+
+  if (ics1->user_conv_p || ics1->kind == ck_list)
     {
       conversion *t1;
       conversion *t2;
 
       for (t1 = ics1; t1->kind != ck_user; t1 = t1->u.next)
-	if (t1->kind == ck_ambig || t1->kind == ck_aggr)
+	if (t1->kind == ck_ambig || t1->kind == ck_aggr
+	    || t1->kind == ck_list)
 	  break;
       for (t2 = ics2; t2->kind != ck_user; t2 = t2->u.next)
-	if (t2->kind == ck_ambig || t2->kind == ck_aggr)
+	if (t2->kind == ck_ambig || t2->kind == ck_aggr
+	    || t2->kind == ck_list)
 	  break;
 
       if (t1->kind != t2->kind)
diff --git a/gcc/testsuite/g++.dg/cpp0x/initlist44.C b/gcc/testsuite/g++.dg/cpp0x/initlist44.C
new file mode 100644
index 0000000..fbe0ea3
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/initlist44.C
@@ -0,0 +1,5 @@ 
+// { dg-options -std=c++0x }
+
+#include <initializer_list>
+
+auto value = std::initializer_list<int>{ 1, 2, 3 };